<div class="row">
  <div class="col-md-4 col-sm-6 input-group mb-3">
    
      <div class="input-group-prepend">
        <span class="input-group-text">Ek Özellik durumu: </span>
      </div>  
           <select id="ozellik" class="form-control is-info" name="ozellik">
              <option selected disabled>Seçim yapın…</option>
              <option value="1">Var</option>
              <option value="2">Yok</option>
            </select>
   </div>
 
<!-- Bu alan Ek Özellik durumu 1 ise görünsün yoksa gizlensin-->
            <div class="col-md-2 col-sm-6 input-group mb-3" >
              <div class="input-group-prepend">
                <span class="input-group-text">Tipi: </span>
              </div>  
              <input type="text" class="form-control" name="tip">
          </div>       
    
          <div class="col-md-2 col-sm-6 input-group mb-3">
              <div class="input-group-prepend">
                <span class="input-group-text">Rengi: </span>
              </div>  
              <input type="text" class="form-control" name="renk">
          </div>  
<!-- Bu alan Ek Özellik durumu 1 ise görünsün yoksa gizlensin-->
</div>